Bridges have been enhanced with functions that improve performance, security, availability, and manageability. Specific capabilities include
Preventing some types of frames from being forwarded to parts of a LAN. This is done to eliminate superfluous traffic or to impose some security constraints. An administrator manually configures filtering rules to be applied to frames. Filtering is described in this chapter.
Eliminating single points of failure by installing backup bridges and creating backup links between bridges. The Spanning Tree Protocol (STP) is the most popular backup facility. The Spanning Tree Protocol is introduced in this chapter and is studied in detail in Chapter 13, "The Spanning Tree Protocol."